Polarizable electrodes of the above-described type have been used in electrochemical processes, especially for chemical synthesis, electrolysis, in galvanic cells for energy storage, as sensors and as corrosion preventors.
In the use of an electrode, there is a requirement that the electrode have a minimum current density (of current transferred to the electrolyte) and a certain minimum service life. This value is given in mA/cm.sup.2. Furthermore, a total delivered-current density whose value is given in mAh/cm.sup.2, over this certain predetermined lifetime is required.
These values are determined by selection of suitable materials for use in a certain electrolyte. Naturally, the material costs play a substantial role. To reduce these costs currently for many applications, one turns to electrodes which comprise a highly conductive electrical conductor, advantageously made of metal or carbon, which is covered by a polymer which was made electrically conductive by the addition of conductive additives.
Since this kind of electrode has, for most applications, a electrically conductive plastic of insufficient activity to guarantee the required minimal exchange current density, the active surface of the electrically conductive plastic sheath has had to be improved by suitable treatment, including roughening or application of an additional active layer, which includes a binding agent in minimal proportions and an electrically conductive component in comparatively larger proportions, which guarantees an increase of the surface activity of the electrode. Truly satisfactory results have generally not been obtainable with this known electrode.